In the treatment of certain medical conditions it is desirable to provide a traction force to a patient's limb or limbs. Examples include distraction of the hip for hip arthroscopy or distraction of fractures of the leg bones in order to re-align the broken bones to ensure correct healing (‘fracture reduction’). In each of these cases, tension is applied to the patient's lower limb or foot. In order to maintain the traction force, it is necessary to apply a counter-force to prevent the patient's body being pulled off the operating table.
Various means have been developed to apply this counter-traction force, including harnesses and patient positions that use the patient's weight as the counter-force, however the most common approach is to provide a cylindrical post (called a ‘perineal post’) located at the patient's groin. In this position, traction force is usually applied to both the operative and non-operative limb to prevent the patient's pelvis rotating about the perineal post.
Examples of such apparatus are described in U.S. Pat. No. 1,697,121 (Knebel), U.S. Pat. No. 2,658,507 (Neufeld) and numerous others, generally called ‘fracture tables’. Variations of fracture tables provide means to apply and adjust traction forces using screw mechanisms or suspended weights (see U.S. Pat. No. 4,802,464 (Deprez) and U.S. Pat. No. 3,088,460 (Wright)).
Although this technique for applying limb traction has been in use for more than 100 years, it still presents a risk of significant injury to the patient. Anatomical structures in the groin in both the male and female are delicate and can suffer grievous injury if the perineal post applied force directly along the midline. In males, damage to the perineal nerve can cause loss of sensation in the penis, whereas in the female, damage to the labia can result.
For this reason, the perineal post is generally well padded and located off-centre in the patient's groin to avoid direct application of the traction force to the mid-line of the patient's groin. Various types of perineal posts are known in the art, all generally intended to distribute the force on the perineum over a large area to minimize the pressure applied to the patient's tissue.
A common failing of all fracture tables and perineal posts know in the art is that there is no means to measure and display the force being applied to the perineum, nor the direction of the force, during surgery. Distal traction devices such as screws or weights can easily be (and sometimes are) equipped with indicating scales to show the amount of traction force applied. Unfortunately, such indicating scales are usually not visible during surgery as they are under the surgical drapes or otherwise obscured, and do not indicate the magnitude or direction of the force applied to the patient's groin. Furthermore, during the course of surgery, it may be necessary to alter the direction or magnitude of the traction force applied to the patient's limb in order to provide visualization of or access to the surgical site. When such changes in the direction and magnitude of the traction force are made, these indicating scales do not provide adequate feedback to the surgeon.
In summary, current fracture tables depend on traction applied through the lower limb, countered by a perineal post. In the surgical setting, there is no indication of the traction force applied to the operative or non-operative limb visible to the surgeon, nor is there any indication of the counter-traction force applied by the perineal post or the direction of the force applied to the patient's groin.
The object of the current invention is to provide means for measuring and displaying to a surgeon the traction force applied to the patient's operative and non-operative limbs, to measure and display the counter-traction force applied to the patient's perineum by the perineal post, and to provide an indication as to the direction of application of the force to the patient's perineum by the perineal post. This will ensure that the surgeon is aware if the traction force as applied from time to time during surgery is exceeding acceptable limits, or if the direction of the force applied to the patient's perineum by the perineal post poses a risk to the fragile structures of the patient's groin.